Carrotting of fibrous materials



United States Patent Office 3,377,132 CARRO'ITING F FIBROUS MATERIALS Thomas Barr, Stockport, and Frank E. Higginbottom,

near Oldham, England, assignors, by mesne assignments, to Hat & Felt Laboratories, Ltd., 'a corporation of Great Britain No Drawing. Filed July 29, 1964, Ser. No. 386,056

4 Claims. (Cl. 8-112) ABSTRACT OF THE DISCLOSURE A process to improve the feltability of for or hair by treatment with a composition consisting essentially of a phosphonium compound of the general formula formula C H OH or C H where n. can have integral values of 1 to 4 inclusive and subsequently drying.

This invention concerns the carrotting of fibrous material such as hair and fur and is particularly, though not exclusively, concerned with such a process when used to carrot the fibres for the production of felt for hats, caps and the like.

As is known certain fur or hair fibres possess only a limited ability to felt and although when subjected to heat, moisture and mechanical working, webs of these materials will felt by shrinking and consolidating, the felt produced is not of sufficient strength and density to be used in hat manufacture.

To overcome this disadvantage the fur is subjected to a carrotting process which consists of treating the fibres with a chemical compound or compounds which react with the protein of the fur. The fur is treated in situ on the skin in such a way that only the tip portion of the fibre is exposed to the action of the agent. The furbearing skins are dried at elevated temperatures usually in a hot air oven. The chemical system traditionally used for carrotting comprises mercury dissolved in aqueous nitric acid. The disadvantages of this process are well known and include:

(1) The solution is toxic and corrosive.

(2) Furs treated with mercury-containing carrotting agents are discoloured and can be excessively damaged during drying which is an integral part of the carrotting process.

(3) Such furs are stored for months before use to mature.

An appreciation of these and other disadvantages has led to the development of carrotting agents which do not contain mercury, the so-called non-mercuric carrotting agents. These. agents are applied to fur in the same way as mercuric carrotting agents and a drying treatment at periods of up to three elevated temperatures is required. Non-mercuric agents are less toxic than mercuric agents, but, because mostof them contain nitric and other oxidising acids, corrosion problems are not eliminated. Discolouration of the fur is minimised if non-mercuric agents are used and the fur may, if necessary, be used without maturing. This type of process is far from ideal in that to produce a fur of a sufiiciently high feltability to make felt it is necessary to degrade the fibre more than when mercuric agents are employed. The conditions of treatment, when .non-mer- 3,377,132 Patented Apr. 9, 1968 curic agents are used, have to be much more closely controlled than when mercuric agents are used, if a satisfactory product is to :be obtained.

It has 'been generally accepted that on carrotting two reactions are essential if felt of acceptable properties is to be produced. Firstly, it is necessary to break the disulphide bonds of the keratin. Secondly, it is claimed that limited breakdown of the amide bonds of the main protein chain must occur. Hitherto it has been assumed that reaction of protein fibres with mercuric carrotting agents produces both disulphide bond fission and suificient amide bond fission to produce the desired effect, whilst non-mercuric agents produce disulphide bond fission together with excessive amide bond breakdown.

We have found, and this forms the basis of the present invention, that agents which react exclusively with the disulphide bonds of the keratin in such a way that some rebuilding of these bonds occurs during the felting process, are effective as carrotting agents.

According to the present invention fur or hair fibres are treated with an aqueous solution of a phosphonium compound having the following general formula:

where X- may be any monobasic anion preferably acetate or chloride and R is of the general formula C H OH and R R and R may be of general formula C H O-H or C H r where n may have integral values of one to four inclusive.

The groups R R R and R may be chosen as thus indicated above and may be similar or different. Typical examples include:

1 ornon I HOHzCP+.CHzOHCl- OHiOH Tetrakis (hydroxymethyl) phosphonium chloride (liH OH HOH504 P -OlH3OH0 OCCH3 .HgoH

Tetrakis (hydroxybutyl) phosphonium acetate CHzOH H C P+C H C1- laHi Tripropyl hydroxymethyl phosphonium chloride Treatment of the skins with aqueous solutions of the preferred agents may be carried out by any of the commercial methods of the industry, such as, hand brushing, machine brushing, machine roller or spray application, or by pad mangling. The aqueous solutions may be applied without addition of other compounds and as solutions buffered to any pH value in the range 0.5 to 9.5.

A- method used widely in the industry is to apply aqueous solutions of carrotting agents to the skins such that the fur absorbs a weight of solution approximately equal to the weight of fur. The ratio of the weight of solution applied, to the weight of fur to which it is applied is hereinafter referred to as the liquor to fur ratio. In the present invention an amount of the preferred agent in the range 0.5 to 15.0 parts by weight per parts of fur may be applied but we prefer to apply 0.5 to 6.0 parts of active agent per 1 00 parts of fur at liquor to fur ratios in the range 0.0'1 to 2.00. After treatment the fur may be dried in a hot air oven or by infra-red radiation. However, the present invention differs from previously used processes in that the drying operation is not an integral part of the process, hence drying can also be effected at ambient conditions of temperature and humidity. Whichever of the methods described above is used, no discolouration of the fur occurs. Fur treated with any of the preferred agents may be used in the manufacture of hat felts immediately after it has been removed from the skin but if it is required to store such fur this may be done without loss of feltability. Further advantages of fur treated with any of the preferred agents when conditions of treatment are suitable include:

(1) The felt can have a tensile strength greater than the tensile strength of felt made from the same quality of mercuric carrotted fur under similar conditions.

(2) Substantial reductions in the time required to felt fur treated with selected agents can be obtained in comparison with the time taken by mercuric carrotted fur of the same quality.

(3) Felts made from fur treated with the preferred agents are of superior colour and handle to felts made from conventionally carrotted furs of similar quality.

(4) Furs treated according to the present invention can be made into felts of high density and strength by planking in water.

The invention is illustrated but not limited by the following examples.

Example I Eighteen fur-bearing rabbit skins of the quality known in the industry as petit bon. were brushed on the furbearing side with an aqueous solution containing 1.0% w./v. of tetrakis (hydroxymethyl) phosphonium chloride hereinafter referred to as T.H.P.C. The liquor to fur ratio was 1.00.

The skins were allowed to dry under ambient conditions of temperature and humidity for 16 hours before the fur was cut from the skins. The fur was passed through-a blowing machine to remove guard hairs and skin fragments and then subjected to the usual processing sequence of forming, hardening and planking. During the planking process the acidity was controlled in such a way that the felt hat bodies contained 3i0.2% sulphuric acid. A sample of mercuric carrotted fur of similar quality was processed at the same time through the same machines. When compared with the felt made from mercuric carrotted fur, the felt made from T.H.P.C. treated fur felted at the same rate, had marginally higher tensile strength, was of superior handle and was not discoloured.

Example II Example III 36 fur-bearing rabbit skins of petit bon quality were treated with'an aqueous solution containing 4.8% w./v. of T.H.P.C. the liquor to fur ratio being 0.86%, using the methoddescribed in Example 1. After treatment 18 skins were dried under ambient room conditions of temperature and humidity while the remainder were dried in a forced draught air oven at 60i2 C. for two hours. After drying both batches of skins, the procedure adopted for the manufacture of hats from each fur was that described in Example I.

The number of multi-rollcr passes required to felt the bodies to size and the tensile strength of the felt were noted and appearin Table I.

TABLE I Concentration Drying Passes on Tensile of agent Conditions multi-roller Strength (percent) (lb./1n.

4. 8 16 hours at 20 C 62 (300 4.8 Zhours at 60 C 53 I54 Hat bodies made from each fur were then dyed, blocked and finished when the hat bodies were judged to have a clarity of colour and a handle superior to those made from mercuric carrotted fur.

Example IV Three batches of fur-bearing rabbit skins of petit bon" quality each containing sixty skins were treated as follows:

Batch l.-An aqueous solution containing 5.0% w./v. T.H.P.C. and buffered to pH 2.5 by the addition of sodium hydroxide, was applied by hand brushing to a liquor to fur ratio of 0.69.

Batch 2.An aqueous solution containing 5.0% w./v. T.H.P.C. and buffered to pH 5.5. by the addition of sodium hydroxide, was applied by hand brushing to a liquor to fur ratio of 0.71.

Batch 3.An aqueous solution containing 5.0% w./v.

" T.H.P.C. and buffered to pH 8.7 by the addition of sodium hydroxide was applied by hand brushing to a liquor to fur ratio of 0.69.

The skins were dried coupled together in pairs with the fur sides touching in a forced draught air oven at 6012 C. for 2 /2 hours. The fur was cut from the skins and subjected to the processing sequence described in Example I. The number of multi-roller passes required and the tensile strength of the felts were measured and are displayed in Table II.

The hat bodies were judged to be of superior handle and to have a better clarity of colour than hat bodies made from mercuric carrotted fur of similar quality.

Example V 24 fur bearing rabbit skins of petit bon quality were treated by hand brushing with an aqueous solution containing 5.6% w./v. of tetrakis (hydroxymethyl) phosphonium acetate at a liquor to fur ratio of 0.94. 24 similar skins were treated by hand brushing with an aqueous solution containing 6.32% w./v. of tributyl hydroxymethyl phosphonium chloride at a liquor to fur ratio of 0.64.

Each batch of skins was dried separately under ambient conditions of temperature and humidity for 16 hours when the fur was cut from the skins and made into hat bodies using the processing sequence described in Example 1. The number of multi-roller passes required and the tensile strengths of the felts were measured and are displayed in Table 111.

The hat bodies were judged to 'be of superior 'handle and have a better clarity of colour than hat bodies made from mercuric carrotted fur of similar quality.

Fur cut from rabbit skins treated in the Way described in Example III and dried in a forced draught air oven at 60:2" C. for two hours was subjected to the sequence of processes described in Example I with one exception. The acid normally added to the liquor in the multi-roller planking machines was omitted and the bodies were felted down to size in water only. The number of multi-roller passes required to shrink the body to of its original size was found to be 64. The felt so produced had a tensile strength of 579 (lb./in. and a density of 0.2005 (oz./in. The bodies were dyed, blocked and finished when they were judged to be of attractive finish and handle.

Example VII 18 fur-bearing hare-skins of the quality known in the trade as Moyenne Arate were treated on a roller carroting machine with an aqueous solution containing 2.5% w./v. T.H.P.C. at a liquor to fur ratio of 0.83. After treatment the skins were dried for 16 hours under ambient conditions of temperature and humidity. The fur was subjected to the processing sequence described in Example I. The tensile strength of the felt was found to be 774 (lb./in. and the bodies were judged to be of superior colour and handle to bodies made from mercuric carrotted hares fur of a similar quality.

Example VIII 240 fur-bearing rabbit skins of the quality known as BOB entire were treated by machine brushing with an aqueous solution containing 5.0% W./v. T.H.P.C. the liquor to fur ratio being 1.80. The fur was subjected to the processing sequence described in Example I. The felting rate of the T.H.P.C. treated fur was superior to that of mercuric carrotted fur of similar quality. The hat bodies made from the T.H.P.C. treated fur had a higher tensile strength and were judged to have a clarity of colour and a handle superior to that of hat bodies made from the above mentioned mercuric carrotted fur.

What is claimed is:

1. A process to improve the feltability of 'fur or hair by treatment with a composition which consists essentially of an aqueous solution containing a phosphonium compound of general formula where X may be any monobasic anion preferably acetate (CH COO) or chloride (Ci and R is of general formula C H OH and R R and R may be of general formula C H OH or C I-I where n can have integral values of l to 4 inclusive and subsequently drying.

2. A process as described in claim 1 in which the weight of the selected compound lies in the range 0.5 to 15.0 parts by weight of agent per parts by weight of fur or hair fibre at a liquor ratio between 0.01 and 2.00.

3. A process as described in claim 1 in which the pH of the aqueous solution of the selected compound is adjusted within the range 0.5 to 9.5 by the addition of a suitable electrolyte.

4. A process as described in claim 1 in which the fur is dried under ambient conditions of temperature and humidity.

References Cited UNITED STATES PATENTS 2,810,701 10/1957 Reeves et a1 2'6029.4

NORMAN G. TORCHIN, Primary Examiner. J. P. BRAMMER, Assistant Examiner. 

